Spiral Matrix II

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n = 3,

You should return the following matrix:

[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]

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  Array

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class Solution {
public:
    vector<vector<int>> res;
    vector<vector<int> > generateMatrix(int n) {
        if(n<0)
            return res;
        else if(n==1)
        {
            vector<int> tmp;
            tmp.push_back(1);
            res.push_back(tmp);
            return res;
        }
        int ** arr=new int*[n];
        for(int i=0;i<n;i++)
        {
            arr[i]=new int[n];
            memset(arr[i],0,sizeof(int)*n);
        }
        //vector<int> bit(n*n,0);
        int count=0;
        int num=1;
        int x=0;
        int y=-1;
        while(num<=n*n)
        {
            if(count==0)
            {
                y++;
                while(y<n&&arr[x][y]==0)
                {
                    arr[x][y]=num++;
                    y++;
                }
                count=(count+1)%4;
                y--;
            }
            else if(count==1)
            {
                x++;
                while(x<n&&arr[x][y]==0)
                {
                    arr[x][y]=num++;
                    x++;
                }
                count=(count+1)%4;
                x--;
            }
            else if(count==2)
            {
                y--;
                while(y>=0&&arr[x][y]==0)
                {
                    arr[x][y]=num++;
                    y--;
                }
                count=(count+1)%4;
                y++;
            }
            else if(count==3)
            {
                x--;
                while(x>=0&&arr[x][y]==0)
                {
                    arr[x][y]=num++;
                    x--;
                }
                count=(count+1)%4;;
                x++;
            }
        }
        
        for(int i=0;i<n;i++)
        {
            vector<int> tmp;
            for(int j=0;j<n;j++)
                tmp.push_back(arr[i][j]);
            res.push_back(tmp);
        }
        
        return res;
        
    }
};